Fixed mistakes and missing semicolon in array
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@ -1,26 +1,26 @@
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# Array
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The type of array is `[T; Lengh]`, as you can see, array's lengh is part of their type signature. So their length must be known at compile time.
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The type of array is `[T; Length]`, as you can see, array's length is part of their type signature. So their length must be known at compile time.
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For example, you cant initialized an array as below:
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For example, you cant initialize an array like below:
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```rust
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fn init_arr(n: i32) {
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let arr = [1; n];
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}
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```
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This will cause an error, because the compile have no idea of the exact size of the array in compile time.
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This will cause an error, because the compiler has no idea of the exact size of the array at compile time.
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1. 🌟
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```rust,editable
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fn main() {
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// fill the blank with proper array type
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// Fill the blank with proper array type
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let arr: __ = [1, 2, 3, 4, 5];
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// modify below to make it work
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// Modify the code below to make it work
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assert!(arr.len() == 4);
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println!("Success!")
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println!("Success!");
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}
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```
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@ -28,16 +28,16 @@ fn main() {
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```rust,editable
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fn main() {
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// we can ignore parts of the array type or even the whole type, let the compiler infer it for us
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// We can ignore parts of the array type or even the whole type, let the compiler infer it for us
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let arr0 = [1, 2, 3];
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let arr: [_; 3] = ['a', 'b', 'c'];
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// fill the blank
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// Arrays are stack allocated, `std::mem::size_of_val` return the bytes which array occupies
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// A char takes 4 byte in Rust: Unicode char
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// Fill the blank
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// Arrays are stack allocated, `std::mem::size_of_val` returns the bytes which an array occupies
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// A char takes 4 bytes in Rust: Unicode char
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assert!(std::mem::size_of_val(&arr) == __);
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println!("Success!")
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println!("Success!");
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}
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```
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@ -46,13 +46,13 @@ fn main() {
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```rust,editable
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fn main() {
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// fill the blank
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// Fill the blank
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let list: [i32; 100] = __ ;
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assert!(list[0] == 1);
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assert!(list.len() == 100);
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println!("Success!")
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println!("Success!");
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}
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```
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@ -60,10 +60,10 @@ fn main() {
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```rust,editable
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fn main() {
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// fix the error
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// Fix the error
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let _arr = [1, 2, '3'];
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println!("Success!")
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println!("Success!");
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}
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```
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@ -73,28 +73,28 @@ fn main() {
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fn main() {
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let arr = ['a', 'b', 'c'];
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let ele = arr[1]; // only modify this line to make the code work!
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let ele = arr[1]; // Only modify this line to make the code work!
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assert!(ele == 'a');
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println!("Success!")
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println!("Success!");
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}
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```
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6. 🌟 Out of bounds indexing causes `panic`.
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```rust,editable
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// fix the error
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// Fix the error
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fn main() {
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let names = [String::from("Sunfei"), "Sunface".to_string()];
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// `get` returns an Option<T>, it's safe to use
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// `Get` returns an Option<T>, it's safe to use
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let name0 = names.get(0).unwrap();
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// but indexing is not safe
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// But indexing is not safe
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let _name1 = &names[2];
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println!("Success!")
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println!("Success!");
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}
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```
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